1. Field of the Invention
The invention relates generally hand-held computer terminals and particularly to hand-held, battery powered computer terminals. The invention is applicable, for example, to portable data collection terminals or interactive data processing terminals which may be used in operations relating to inventory control and stock management, and to various other data processing operations in which information for data entry is made at spatially scattered locations and the data terminal is moved among such different entry points to locally enter data into the terminals. The scope of usage for the subject invention may consequently include mobile customer service operations and route delivery operations.
2. Discussion of the Prior Art
Recent years saw the introduction of hand-held computer terminals, also referred to as data terminals, of both batch processing and continuously on-line or interactive data terminals. Though a small size appears desirable for a portable data terminal and advances have already been made in that area, enhancements in state of the art terminals in support of the portability appears desirable. While size and weight are typically not of concern to permanent computer installations in an office environment, they are of concern with respect to the portability of hand-held data terminals. One of the requirements which affect the portability of hand-held data terminals is the weight added and the space required by self-contained power sources, such as batteries. The problem of self-contained power sources becomes more acute when commercial type applications of hand-held data terminals require extended periods of power consumption, in that charge periods for power supplies would interfere with normal periods of use. Battery packs consequently require space and add considerable weight to portable, hand-held data terminals.
Batch type data terminals require substantial data storage capabilities, referred to as memory capacity. Data of an entire work cycle, such as a normal workday or an entire delivery route, need to be temporarily stored in memory banks. Typically, storage requirements further include extensive data banks, such as customer and product lists, credit information and product availability information, in addition to operational protocols. Information entered into and temporarily stored in batch type terminals is then typically transferred or up-loaded to a central processing unit only once at the end of a workday or at the conclusion of a task.
Interactive type terminals typically require less space for memory. The latter type terminals conveniently use FM transmission links to interact with a central processing station. The FM link, for example, allows a number of inventory clerks to remain in contact with a single, stationary central processing unit while the clerks may move about on the warehouse floor taking the terminals from one to the next of various shipment or merchandise stores. Thus, the single central processing unit maintains up-to-date records of the entire stock inventory. The interactive type terminals, though requiring less space for self-contained memory, trade off the saved space for the FM transceiver unit. Thus, both batch type data terminals and interactive data terminals have similar minimum volumetric needs for housing the elements for their respective, desired functions.
Hand-held data terminals, in addition to the discussed minimum size and weight requirements, desirably should meet other needs which typically would not be considered significant for office-type computer installations. Some of the discussed requirements appear to create problems of trade-offs with other features for such terminals.
One of the problems of such hand-held computer or data terminals relates to their size, in that minimizing size appears important to enhance the ease of manipulating the terminals, while features may become more bulky, such as power supplies because of the terminals being self-contained or portable. Another problem is that, even at a seemingly low weight in comparison to other computer terminals, users of portable terminals working data processing entries with the terminals over prolonged time periods tend to tire from holding the terminals in their hands. Operating the terminals typically involves repeatedly lifting the unit to a proper reading level while making data entries or while retrieving information from the central processing station. In typical operations of this type, rest periods for the users are needed.
The portability problem of data terminals relates to a minimum practical size of an upper surface for such data terminals, below which the upper surface appears to become increasingly user unfriendly. The upper surface include a practically sized window area for a digital display and an equally significant area within which the keyboard is located. Practical size limitations on these components appear to establish a lower practical size limit for upper surfaces of the data terminals. Though compromises have been attempted to reduce the size of the keyboard or display, typically it has been found that attempts to reduce the size of the upper surface to below a practical minimum renders resulting terminals commercially less acceptable. A compressed display of data is more likely to generate data misinterpretation by the user, particularly under at times less than ideal lighting conditions in a warehouse, which may lead to significant errors in inventory control. A compressed keyboard is more likely to cause errors in data entry and rejection of the units by users.
For temporarily relaxing the grip on the terminals, but also because the need for other manual work may interrupt the operation of the terminals, users may place the terminals aside for short periods of time. The terminals appear to be exposed to more than the usual hazards during such periods of being laid aside. The terminals may, for example, fall from shelves or tractor hoods, or may be stepped on when temporarily placed on a floor. A degree of impact or crush resistance for hand-held data terminals appears to be a desirable feature.
But even while being carried about, many practical work environments for hand-held data terminals seem to subject the terminals to greater hazards than a typical office computer environment. For example, the terminals are likely to be used in dusty warehouses. The terminals may also be affected by inclement weather conditions in conjunction with certain outdoor uses, such as at airports or in truck yards. The desirability of rugged and weather resistant terminals seems apparent On the other hand, hand-held data terminals which are rugged and weather resistant seem to require trade-offs with respect to features for maintaining or enhancing the portability of the hand-held data terminals. Constant effort has been placed on providing portable, hand-held data terminals with an optimization of the above discussed characteristics.